This application relates to a cryogenic fluid supply system with reduced or minimized loss of cryogenic fluid. More specifically, this application relates to a cryogenic fluid supply system of the type commonly use to supply medical oxygen on an intermittent basis in which the loss of cryogenic fluid is significantly reduced from the losses normally experienced by a conventional system.
In a conventional cryogenic fluid supply system, cryogen is supplied from a tank containing liquid cryogen, as well as some vapor cryogen in the headspace above the liquid. Typically, liquid is withdrawn from the bottom of the tank and vaporized for an end use. For example, conventional systems like this are often used for supplying medical oxygen from a liquid oxygen tank or dewar. However, because many uses are intermittent, a conventional system may experience significant losses of cryogen when the end use is temporarily stopped. Specifically, any liquid cryogen remaining in the supply lines and vaporizer takes on heat from the ambient environment, and as the resultant pressure increase pushes some of the remaining liquid back into the tank, some of that heat is also carried back into the tank. This causes the tank to increase in pressure. Ultimately, the tank needs to vent to relieve some of the excess pressure buildup, resulting in loss of cryogen. An object of the presently described system and method is to overcome this problem with conventional systems.